When Jesus left from the Mount of Transfiguration, he again foretold his crucifixion. At this point, he sought to specifically train the disciples in temperament, in matters of grace, humility, kindness.

The disciples, knowing that they were on a trip toward Jerusalem, but still not rightly understanding their progress:

1 At that time the disciples came to Jesus, saying, “Who is the greatest in the kingdom of heaven?” Matthew 18:1 (ESV)

Bruce makes the interesting observation that Jesus did not reject their question, rather he answered it:

For be it observed, Jesus did not summarily dismiss the question, who is greatest in the kingdom, by negativing the existence of distinctions therein. He said not on this occasion, He said not on any other, “It is needless to ask who is the greatest in the kingdom: there is no such thing as a distinction of greater and less there.” On the contrary, it is implied here, and it is asserted elsewhere, that there is such a thing. According to the doctrine of Christ, the supernal commonwealth has no affinity with jealous radicalism, which demands that all shall be equal. There are grades of distinction there as well as in the kingdoms of this world. The difference between the divine kingdom and all others lies in the principle on which promotion proceeds. Here the proud and the ambitious gain the post of honor; there honors are conferred on the humble and the self-forgetful. He that on earth was willing to be the least in lowly love will be the great one in the kingdom of heaven.

But Jesus answered the question by going at the matter of how they evaluated such things. He went to the issue of their temperament, they basic orientation to the world and sought to correct their judgment of such things.

Jesus taught them by use of a living parable:

2 And calling to him a child, he put him in the midst of them 3 and said, “Truly, I say to you, unless you turn and become like children, you will never enter the kingdom of heaven. 4 Whoever humbles himself like this child is the greatest in the kingdom of heaven.” Matthew 18:2–4 (ESV)

Rather than reject the notion of greatness, he goes at the means by which they had determined to measure greatness:

The higher we rise in the kingdom the more we shall be like Jesus in this humbling of Himself. Childlikeness such as He exhibited is an invariable characteristic of spiritual advancement, even as its absence is the mark of moral littleness. The little man, even when well-intentioned, is ever consequential and scheming,–ever thinking of himself, his honor, dignity, reputation, even when professedly doing good. He always studies to glorify God in a way that shall at the same time glorify himself. Frequently above the love of gain, he is never above the feeling of self-importance. The great ones in the kingdom, on the other hand, throw themselves with such unreservedness into the work to which they are called, that they have neither time nor inclination to inquire what place they shall obtain in this world or the next. Leaving consequences to the great Governor and Lord, and forgetful of self-interest, they give their whole soul to their appointed task; content to fill a little space or a large one, as God shall appoint, if only He be glorified.

Jesus then took the related matter. Not only must they seek a humility which cares nothing for personal greatness and only for the glory of God, they must be willing to receive all who come, and to do so for the sake of Jesus, himself:

Bruce notes the connection between a gentle, humble spirit and a willing acceptance of others:

This transition of thought from being like a child to receiving all that of which childhood in its weakness is the emblem, was perfectly natural; for there is a close connection between the selfish struggle to be great and an offensive mode of acting towards the little. Harshness and contemptuousness are vices inseparable from an ambitious spirit. An ambitious man is not, indeed, necessarily cruel in his disposition, and capable of cherishing heartless designs in cold blood.

It needs to be seen here, as elsewhere, that discipleship requires a constant movement toward the Lordship of Jesus. Jesus explicitly commands these men to forgo their person ambition, protection, good for the sake of Jesus. They ask about their rewards and he explains that rewards will be given only to those who seek Jesus and not something other than him.

Sin constantly tempts us to seek our own

Poor soul, the centre of my sinful earth,

Shakespeare, Sonnet 146. We were not created to be our own center, our own ground. We were created for a Creator, and our goal is to be him. Thus, in discipleship, Jesus was seeking to wean these men from their pursuits after their personal good and to seek that good which comes from God, alone.

And, in the manner of which things concerning Christ work, as one seeks Christ, these attributes of humility and love of the weak come necessarily, automatically along. This helps us to understand why humility and graciousness can be so difficult obtain: we seek them as if they were objects we could rightly possess without Jesus. However, when we rightly seek Jesus, we will receive the love and humility he commands:

Jesus further directed the attention of His disciples to the sublimest example of humility. For that love shows that there was not only no pride of greatness in the Son of God, but also no pride of holiness. He could not only condescend to men of humble estate, but could even become the brother of the vile: one with them in sympathy and lot, that they might become one with Him in privilege and character. Once more, in making reference to His own love as the Saviour, Jesus pointed out to His disciples the true source of that charity which careth for the weak and despiseth not the little. No one who rightly appreciated His love could deliberately offend or heartlessly contemn any brother, however insignificant, who had a place in His Saviour-sympathies. The charity of the Son of man, in the eyes of all true disciples, surrounds with a halo of sacredness the meanest and vilest of the human race.